The Role of V-Species and O-Species on Controlled-Hydrogen-Reduction VOx Surfaces in Cyclohexane Oxidation

Graphical A simple and controllable defect construction method for vanadium-oxygen catalysts through hydrogen reduction with TCD detector were used to control the reduction state of CHR-VOx which determines the V-Species and O-Species. Furthermore, the structure-performance relationship and the catalytic pathway were assumed, multi-liganded-oxygen and V 4+ species are the key parameters. A series of controlled-hydrogen-reduction VO x (CHR-VO x ) were prepared after our controllable hydrogen treatment, and CHR-VO x were controlled to be reduced to the states dominated by V 5+ and V 4+ species, subsequently the catalytic roles of V-species and O-species for cyclohexane (CHA) oxidation were explored. As expected, the surface properties of CHR-VO x have occurred remarkable change resulting in a significantly improvement on catalytic performance determined by V-species and O-species. The reduction behavior of the properties was recognized by XPS and Raman. Generally, the moderate-reduced CHR-VO x which possessed most 78.7 % multi-liganded-oxygen ( L O) performed the best conversion for CHA (11.8 %), and the over-reduced CHR-VO x with a large content of V 4+ species (33 %) performed a best selectivity for adipic acid (44.3 %). In this case, L O sites were regarded as the active site to accelerate the activation of CHA, while V 4+ species were regarded as the oxygen vacancies (OVs) through V 4+ −OV to contribute to the further oxidation to adipic acid.